Elevator control system



Dec. 8, 1953 A. E. FRIBANCE ET AL ELEVATOR CONTROL SYSTEM Filed Oct. 28, 1949 ATTORNEYS.

Patented Dec. 8, 1953 ELEVATOR CONTROL SYSTEM Austin E. Fribance, Rochester, and Thomas F.

Jarvis, Warsaw, N. Y., asslgnors to Watson Elevator Company, Inc., a corporation of New `York Application October 28, 1949, Serial No. 124,208

20 Claims. (Cl. S18-158) This invention relates to electrical elevator and hoist control systems of the variable voltage type.

One of the objects of the invention is tol provide an electrical control system for the purposes aforesaid which provides improved control features and which is reliable and inexpensive to construct and adjust and maintain in operation.

Another object is to provide an electrical control system which may be embodied in standard units adapted to control elevator and hoist mechanisms of various types and capacities by using standard stock control units which may be readily adjusted when installed to suit the particular installation.

A further object is to provide an improved control system which will control the elevator mechanism so as to provide stepless acceleration and deceleration, thereby increasing the riding comfort and reducing shccl loads on the mechanism.

It is also an object to provide a more eiiicient ver tical transportation system.

ln the drawing, the single figure is a straightline schematic diagram ci an elevator control system embodying the invention.

The invention is described in connection with a simple elevator system, but it is to be understood that it may be used in hoist systems and in other more complicated elevator systems or in other mechanisms employing similar drives for other purposes.

Reielring novv to the drawing, We have illustrated an elevator car t as suspended by a cable il which passes over a hoisting drum 5 to a counterweight t. The hoisting drum 5 is xed upon a shaft i operated by a hoisting motor M having an armature 3. The motor M is provided with a shunt eld Winding 9 connected across a pair of supply conductors I0 and il which may be supplied with direct current from a suitable source. A spring-operated brake l2 controlled by an electromagnetic coil I3 is provided for preventinfy operation of the hoisting drum ii when the hoisting motor is deenergized.

A variable voltage system of control is provided for operating the hoisting motor M wherein its armature :l is connected by means of conductors ifiiii in a closed circuit With the armature lit of a generator G; the generator having a separately excited main field Winding l?. The armature It oi the generator is arranged to be driven at a constant speed by means of any suitable drive motor (not shown) The direction and speed of the hoisting motor M are controlled by controlling the dire tio and value of the excitation current for the enerator main eld Winding il. The directiei controlled by a first up direction relay U a first down direction relay D. The value or" the excitation current will be controlled as hereinafter described. 'The operation of the and the down direction relays is controlled by a second up direction relay UR and a second down direction relay DR which, in turn, are controlled by a manually operated control switch mounted in the car in position to be controlled by the car attendant when he desires to effect the starting or stopping of the car. A car-running relay MLB is provided for conditioning the control system for operation when the car is 'to be moved and also for eiiecting the release ci the brat-e it when the car is in operation. Directional relays U and D are controlled by means of the contacts URI and DRI respectively of the directional relays UR and DR. In turn the contacts Uli- U2 or Di-DZ of the relays U or D operate to ccntrol the circuit of the generator shunt field i Any suitable system may be utilized or automatically decelerating the car and stopping it level with a door in response to a stopping operation oi the control switch It. In the present case We have illustrated a pair of high speed levelling control relays UL and DL, and a stopping control relay LR. These relays are operated by a suitable levelling system (not shown) but indicated by contacts lt-til--t A relay HS is provided to control the high speed movement of the car as Will be explained in detail hereinafter; said relay being energized by closing of contact URZ or DR?.

Whereas, many arrangements have been previously devised for the purpose oi'l controlling elevator drive motors so as to oi: n suitable acceleration-deceleration characteristics, the dcvices of the prior art have been deficient in certain respects. For example, certain prior systems have employed mechanical timing devices and thereby obtain pronounced step by step speed changes. In order to overcome these culties, the present invention provides a novel regulating means for stepless controlling of 4the energizaticn of the eld oi the generator supplying current to the driving motor, so that improved accelerating decelerating acteristics may be obtained throughout all starting and stopping operations of the car.

Our control system contemplates controlling the main field il by the use of a pair of gaseous electronic discharge tubes 25 and 2". The tube anodes of the tubes are connected to the secondary winding 32.

It will be obvious that the current supplied by the tubes and 26 to the main eld winding l'I will control the energization of that iield winding and thereby control the output of the generator G. The output of the tube is controlled by providing a means for controlling the energization of the grid 28 of the tube 25. The means for controlling the grid comprises a phase shift network together with a suitable variable DC bias obtained from a cathode resistor; the operation of which is hereinafter more fully described.

The phase shift network comprises a secondary winding 38 of transformer 33 with a center tap 39; a condenser 40, and a resistor 4I. The variable DC bias is obtained by suitably controlling the plate current through a triode tube 42 having anode 43, grid 44, and a cathode 45 heated by a suitable filament (not shown). plate current passes through the cathode resistor 46 which is in the cathode circuit of the tube 42.

A suitable source of direct current is provided through conductors 41--48 which furnishes the plate current for tube 42 and controls the charging of a timing condenser 49 through resistors 50--5I--52, as will be described hereinafter.

The starting of elevator car 2 is controlled by movement by the operator of control switch I8. When switch I8 is moved for the direction desired, such as Up, relay UR closes which in turn closes contacts URI, UR2, and opens UR3. Assuming that the doors and gates have been closed, URI contact will cause relay U to close. This closes UI and U2 so as to connect the generator field supply to the generator field for required polarity for travel in Up direction; when contact U3 closes, it in turn energizes MLB and HS relays. The opening of UR3 contact on UR relay disconnects the leveling system from the control system and allows the car to travel without interference from the leveling control system. This not only allows the car to leave the landing at which it has been parked, but will also allow the attendant to by-pass a landing, if desired.

When MLB relay closes, the generator field winding I1 is disconnected from the loop circuit conductor I4 by opening of MLB 3 contact. The generator field winding I'I is differentially connected directly across the loop circuit when the car is not in motion, for the purpose of preventing residual voltage build up to prevent car movement until called for by the operator. Also', upon closing of relay MLB contact MLB2 closes thereby energizing solenoid I3 and releasing the brake I2. At the same time the contact MLBI is closed, completing the circuit to generator field I1 from the rectifier output through coni ductors 53 and 54. This closing of HS relay causes contact HSI to close and contact HS2 to open. This starts the elevator car 2 which accelerates under control of the grid rectifier tube 25 and the timing condenser 49.

When the attendant desires to stop at a land- This fit

ing, the control switch handle is returned to neutral and the car slows down to a predetermined speed and continues to the landing where it will be automatically stopped by the leveling units I9 or 20 depending upon the direction of travel. The release of the control switch allows relay UR to drop out, which opens contacts URI and UR2, and closes contact UR3. The opening of URI does not deenergize relay U as it is held in by its own contact U2. The opening of contact UR2` causes relay HS to drop out, causing the car to slow down to leveling speed by opening of contact HSI and closing of contact HS2. Opening of contact HSI removes the charging current from the condenser 49, causing the elevator car 2 to start to slow down. The closing of HS2 applies a lower fixed value voltage to the control grid 44 from the resistor network 52, and establishes a fixed value of output voltage from the grid control rectifier tube 25. The value of this voltage is determined by the setting of the slide contact 55 on resistor 52. The setting of slide contact 55 is such as to provide for a low car speed suitable for movement of the car in the leveling zone prior to stopping. Thus, when HSI opens and HSZ closes, the output voltage on conductors 53 and 54 decreases smoothly at a rate predetermined by the setting of the slide contacts 51 and 58 until it reaches a fixed predetermined value as established by setting of the slide contact 55.

The car then continues to travel at leveling speed toward the landing. When it reaches the leveling Zone, contact I9 closes for Up travel. This closes relay UL, causing contact ULI to closel and this completes the circuit to relay U, oy-passing contacts URI and U2. The car continues towards the landing until the leveling unit 2l reaches its zone thereby causing relay LR to close which opens contact LRI. The opening of LRI opens the circuit through U2 and transfers control of relay U to leveling contact ULI. This makes it possible for the leveling unit I9 to stop the car when its contact opens and relay UL drops out and contact ULI opens, thus causing' relay U to drop out and disconnect conductors` 53 and 54 of the rectifier output from the generator field I1. The opening of relay U alsovdeenergizes relay MLB which opens contact MLB2 to open the circuit to brake solenoid I3, thereby permitting the springs to set the brake I2. Contact MLB3 simultaneously closes to connect the loop circuit. At the same time contact MLB4 opens to remove signal voltage from the grid 44 of tube 42, and contact MLBI also opens.

The excitation of generator field I'I is provided by a half wave gaseous grid controlled rectifier tube and a back wave gaseous rectifier tube 2S of the half wave type. Since tube 25 is a half wave rectifier, it will pass current in only one direction when its grid 2B has a potential on it that will allow the tube to conduct current between its anode 21 and cathode 29. Tube 25 willY conduct on the positive half of each cycle of voltage suppiied by the transformer secondary winding 32. Therefore, generator iield I? receives half wave pulses from tube 25, and since ripple characteristics through the generator field i?. By controlling the amount or" current passed through tube '25 it is possible to control the amount of excitation of the generator eld winding il and thus the output of the generator which in turn controls the speed of the motor M and the elevator car.

When no conduction through the tube 25 is desired, as when the car is not moving, a negative bias is applied to grid 28 of sufficient value to render the tube non-conductive- This bias is established by tap 56 on resistor 52, and is set so as to maire the cathode 2?: positive of suiiicient value with respect to the grid 2t, thereby biasing the tube 25 to cut-01T condition. With tap 56 set so that tube 25 will not conduct, the closing of Contact HSI provides a positive voltage on grid lil of tube 42 through the resistor iii?. This is by-passed by condenser di). The chai-gm ing of condenser 39 takes place through the resister te, and this charging current causes a velt age drop through resistor 5E), which slowly builds up to its maximum value until the condenser it is fully charged. Thus, the control grid d oi' tube l2 is slowly made more positive as condenser fis becomes charged. As the grid ill con trols the amount of current passed through tube 42, the voltage drop through the resistor et also changes, reaching a maximum value when condenser de is fully charged. The voltage drop across resistor i6 is combined dierentially with voit-age drop on resistor 5?. between. conductor Il? and tap tit. The increase in voltage across resistor de slowly changes grid 28 to a more posi tive value allowing grid control tube 25 to conduct more and more of each positive half of each cycle.

Since complete control for full conduction or". the positive cycle through tube 25 cannot be obtained by the change of D. C. bias on grid 2S, an A. C. voltage of suitable value produced by the phase shift network is combined with the D. C. bias. This is obtained from secondary winding 38 of transformer 33. Voltage from this winding shifted out or" phase with that or winding 32 by means of resistor 4i and condenser Iii k as is well known in the art. The output of the phase shift circuit is combined with the D. C. bias and serves to control the grid 23 so as to provide control over the full working portion of the positive cycle of tube 25.

The rate of charge of condenser 45 which cone trois acceleration of the car 2 is controlled by the position of tap 5'? on the resistor l. Likewise, the deceleration rate is set by means of tap 5S on resistor 5I. The top speed of the car is adjustably controlled by setting of tap 59 on resistor 52. Thus, rates of acceleration and deceleration, maximum top speed, and leveling speed can be readily adjusted to meet various iield conditions.

Thus, it will be appi'eciated that by reason of the arrangement of the invention, commercially available standard type compound generators may be employed in conjunction with our novel electronic generator field control system to obtain an improved type stepless accelerationdeceleration performance. Hence, improved operation is obtained without resort to use of espensive .and complicated special generator held windings or special control apparatus designed to suit various type generators as produced by present clay manufacturers. A particular feature and advantage of the invention is that it greatly facilitates initial installation adjustment of the generator control equipment because preliminary adjustment for maximum car speed: levelling speed; acceleration and deceleration can be made before the motor-generator set is started up and without requiring movement of the car to check the adjustments. Thus, much of the expense and dificulties and hazards incidental to prior methods of adjustment are eliminated. Also, the system lends itself readily to easy modiication of the speed and acceleration performance characteristics of the oontrolled elevator.

lt will of course be understood that whereas the invention has been shown and described in detail only in conjunction with a simplified eleu vator contr-ol system, it is equally applicable to use in other more complex systems and in combination with any ot -er control devices as may be required to suit different installations.

What is claimed is:

l. A variable speed eievator motive power system comprising a motor having its field winding supplied from a source of electrical energy and a generator connected to supply armature current to said motor, a field winding for said generator, an alternating potential supply, means including a gridecontrolled rectifier for connecting said supply to said generator field winding, an insulating control tube having at least a cath-u ode and a control grid and an anode, an input timing circuit comprising a capacitance and a resistance connected to said control grid, and connections for applying an output voltage furnished by said control tube to the grid of said grid-controlled rectiiier.

2. The invention in accordance with claim l, and a phase-shifting circuit energized from said alternating potential supply, said phase-shifting circuit being connected in series with the potential furnished by said control tube thereby to to extend the region of control of said rectiiier to values beyond that established by the direct current bias derived from said control tube.

3. The invention in accordance with ciaim l5 and means for adjusting the value of said bias potential.

4. The invention in accordance with claim l5, and means for adjusting the value or said bias potential, and means for selectively controlling the rate of increase of potential furnished by said control tube.

5. rihe invention in accordance with claim l5, and means -for adjusting the value or" said bias potential, and means for selectively controlling the rate of decrease of potential furnished by said control tube.

6. The invention in accordance with claim l5, a manually controlled resistor, and means responsive to the condition of said controlled resistor for adjusting the magnitude of said potential.

7. The invention in accordance with claim l5, a manually controlled resistor, and means re-i sponsive to the condition oi said controlled resister for adjusting the magnitude or" said bias potential, and means for selectively controlling the rate of increase of potential furnished by said control tube.

8. The invention in accordance with claim l5, a manually controlled resistor, means responsive to the condition of said controiled resistor for adjusting the magnitude of said bias potential, and means for selectively controlling the rate of decrease of potential furnished by said control tube.

9. The invention in accordance with claim l,

I and means for applying a charging potential to said capacitance to establish a predeterinincdmaximum value of potential applied to thel grid of said rectiiier.

l0. The invention in accordance withV claim l, and means for applying a charging` potential to said capacitance to establish a predetermined maximum value of potential applied tothe grid of said rectier, and means for selectively controlling` the rate of increase, of potentiall furnished by said control tube.

il. The invention in accordance, with claim l, and means for applying a charging potential to, said capacitance to establish a predetermined maximum value of potential` applied to the grid of said rectiiier,l and means for selectively controlling the rate or" decrease ofV potential furnished by said control tube.

12. The invention in accordance with claim l, and means for applying a charging potential to said capacitance to establish a predetermined lower operating value of potential applied to the grid oi said rectifier.

13. The invention in accordance, with claim l, and means ior applying a controlled direct c urrent bias potential between the anode and the grid or said control tube, to control the value of potential furnished oy said control tube,y and means for providing a smooth transition from the maximum value of voltage furnished by the control tube to a predetermined value to` pro-- vide the desired leveling speed of; the elevator car.

14. The invention in accordance with claim` i, and means for biasing said rectifier to cut-off.,

l5. A variable speed elevator motive power systern comprising a motor having its field winding supplied from a source of electrical energy and a generator connected to supply armature current to said motor, a field winding for said generator, and alternating potential supply, means including a grid-controlled rectifier for connecting said supply to said generator field winding, an insulating control tube. having at least a cathode and a control grid and an anode, an input timing circuit comprising a capacitance and a resistance connected to said control grid, connections for applying an output voltage furnished by said control tube to the grid of said grid-controlled rectifier, and means for applying a controlled direct current bias potential between the anode and the grid of said control tube, to control the value of potential furnished by said control tube..

l5. A variable speed elevator motive power systeni comprising a motor having its ileld winding supplied from a source. of electrical energy and a generator connected to supply armature current to said motor, a iield winding for said generator, an. alternating potential supply, means including a grid-controlled rectifier for connecting said supply to said generator field winding, an insulating' control tube having at least a cathode and a control grid and an anode, an input timing circuit comprising a capacitance and a resistance connected to said control grid, connections for applying an Output voltageY furnished by said control tube to the grid of said grid-controlled rectier, and means for applying a controlled direct current bias potential between the anode the grid of said control tube, to control the value of potential furnished by said control tube, and means for selectively controlelfi Sdi

ling the rate of increase of potential furnished by said control tube.

17. A variable speed elevator motive power system comprising a motor having its field winding supplied from a source of electrical energy and a. generator connected to supply armature current to said motor, a eld winding for said generator, an alternating potential supply, means including a grid-controlled rectier for connecting said supply to said generator field winding, an insulating control tube having at least a cathode and a control grid and an anode, an input timing circuit comprising aI capacitance and a resistance connected to said control grid, ccn-4 nections for applying an output` voltage furnished by said control tube to the grid of said Y grid-controlled rectifier, and means for applying a controlled direct current bias potential between the anode, and the grid of said control tube, to control the value of potential furnished by said control tube, and means for selectively controlling the rate of decrease of potential furnished by said control tube.

18. A variable speed elevator motive power system comprising a moto-r having its iield winding supplied from a source of electrical energy andv a generator connected to. supply armature current to said motor, a field Winding :for said generator, an alternating potential supply, means including a grid-controlled rectifier for connecting said supply to said generator field winding, an insulating control tube having at least a cathode and a control grid and an anode, an input timing circuit comprising a capacitance and a resistance connected to said control grid, connections for applying an output voltage furnished by said control tube to the grid of said grid-controlled rectiiier, and a rectifier tube connected across said generator neld Winding and having its cathode connected to that side oi said winding connected to the cathode of said grid-controlled rectier, to provide a low resistance path for the discharge of energy stored` in said generator field' winding by conduction through said grid-controlled rectiiler.

19. A variable speed elevator niotive power systein comprising a motor having its field winding supplied from a source of electrical energy and a generator connected to supply armature current to said nictor, a neld winding for said generator, an alternating potential supply, means including a grid-controlled rectiiier for connecting said, s pply to said generator field winding, an insulating control tube having at least a cathode` and a control grid and an anode, an input timing circuit comprising a capacitance and a resistance connected to said control grid, connections for applying an output voltage furnished by control tube to the grid or said grid-controlled rectifier, and a recti er tube connected across said generator field Winding to provide a low resistance path for the discharge of energy stored in said generator field winding by conduction through said grid-controlled. rectifier.

2G. A variable speed elevator motive power system comprising a motor having its field Winding supplied from a source of electrical energy and a generator connected to supply armature current to said motor, a field winding for said generator, an alternating potential supply, means including a grid-controlled rectifier for connecting said supply to said generator field winding, an insulating control tube having at least a cathode and a control grid and an anode, an input timing circuit comprising a capacitance and a resistance connected to said control grid, connections for applying an output voltage furnished by said conpotential furnished by said control tube, and f means for providing a smooth transition from the maximum value of voltage furnished by the control tube to a, selectable lesser value.

AUSTIN E. ERIBANCE. THOMAS F. JARVIS.

References Cited in the ille of this patent UNITED STATES PATENTS Number Name Date La Roque June 15, 1937 Fath June 28, 1949 

